Devices for the Treatment of Obesity: Modes of Action

Market drivers in the treatment of obesity are strong, and include the fact that there is a significant unmet need: pharmaceuticals by and large do not work well, and may have objectionable side effects. For morbid obesity, the only known effective treatment is gastric bypass. For the hundreds of millions of individuals who are obese but not in the category of morbid obesity, there are very few treatment alternatives. Treatment is not a ‘one size fits all’ situation. The complexity of the human organism, combined with the multifactorial roots of obesity, means that physicians will need to have several options to offer to patients, as one that works well with one patient may not work with another. In addition, the fact that anti-obesity drugs are failing to win the recommendation of the US FDA advisory panels means that the door remains wide open for the development and commercialization of device treatments.

Obesity treatments fall into either drug or device options:

Drugs

Satiety

Malabsorption

Appetite suppression

Combination drugs

Medical devices

Restrictive

Artificial fullness

Malabsorption

Gastric emptying

Appetite suppression

The different medical device options are described below:

Restrictive Devices. Gastric Banding has become one of the most popular bariatric procedures in the USA, Europe, Australia, and South America. A laparoscopic adjustable gastric band is a restrictive device implanted via bariatric surgery and designed for obese patients with a body mass index (BMI) of 40 or greater—or between 35–40 in cases of patients with certain comorbidities that are known to improve with weight loss, such as sleep apnea, diabetes, osteoarthritis, or metabolic syndrome, among others. Initial weight loss is slower than with Roux-en-Y, commonly on the order of 1-2 pounds per week.

Artificial Fullness Devices. These devices are intended to cause a feeling of fullness, hence decreasing the amount of food consumed, include intragastric balloons (and the artificial fullness device in development by EndoSphere device). The intragastric balloon, as its name implies, is a balloon that is placed in the stomach, and then inflated by filling it with air, water or saline, depending upon the particular model. Insertion techniques vary. In general, the collapsed balloons, stiffened by a guide wire, are advanced into the stomach in a manner similar to the insertion of a nasogastric tube. Once in the stomach the balloon is endoscopically evaluated and inflated to varying volumes (ranging from 400–800cc), depending on the manufacturer and model. The filled balloon takes up space in the stomach; less space remains for food, so the patient feels full faster, stops eating sooner, and loses weight. Removal is performed by endoscopic deflation of the devices either by needle deflation through a re-penetrable valve, or needle puncture and removal with a basket or a snare. To date, there are no intragastric balloons approved for use in the US.

Malabsorption Devices. The striking hormonal alterations seen with gastric bypass surgery are causing researchers to reexamine what they know about the biological mechanisms which occur when the duodenum and proximal jejunum are bypassed. In particular, the improvement in insulin sensitivity and glucose metabolism seen with gastric bypass can occur immediately after surgery, well before any significant weight loss has occurred. Malabsorption devices, as the name implies, physically hinder the body’s full absorption of elements of ingested food by imitating a gastric bypass. These devices are intended for temporary placement and are reversible.

Devices to Control Gastric Emptying. Another way to hinder absorption of food is to control the rate of emptying of the stomach by slowing it down. Slower emptying means a greater feeling of fullness, leading the patient to eat less. It may also cause changes in other metabolic hormonal processes. Both the TPS and the TERIS devices are in development, and are not forecast to enter the market before 2012. The Botox solution is also in early stages of investigation.

Appetite Suppression Devices. Devices intended to decrease the appetite generally begin to work when the individual begins to eat. These include gastric electrical stimulation, vagus nerve block, stomach nerve ablation and others.

Currently, only restrictive devices represent a significant market volume, virtually all medical device types will soon begin generating measurable sales as numerous devices now in late development are expected gain approval and be introduced. Simultaneously, over the next few years, appetite suppression drugs and malabsorption drugs will persist (suppression will slightly decline, but malabsorption will steadily grow) while satiety drugs start to accelerate and combination drugs will break free of regulatory stranglehold. The result is that the relative balance of sales between obesity drugs and devices will not change considerably, despite significant changes in the market volumes of each drug and device treatment option.